Two resist method for printed circuit structure

Abstract

Abstract AN IMPROVED METHOD IS PROVIDED FOR PLATING CONDUCTIVE MATERIAL IN A PREDETERMINED PATTERN ON A CONDUCTIVE LAYER THAT IS THEREAFTER ETCHED TO THE SAME PATTERN AS THE PLATED MATERIAL OR IS ETCHED TO THE PATTERN THAT EXTENDS BEYOND THE REGION OF PLATING. TWO LAYERS OF PHOTOSENSITIVE RESIST ARE APPLIED ONE OVER THE OTHER TO THE CONDUCTIVE LAYER. THE FIRST OR INNERMOST RESIST LAYER IS DEVELOPED TO MASK THE CONDUCTIVE LAYER IN THE AREAS THAT ARE LATER TO BE REMOVED BY ETCHING. THE SECOND RESIST LAYER IS DEVELOPED TO EXPOSE REGIONS OF THE CONDUCTIVE LAYER THAT ARE TO BE PLATED. AFTER THE PLATING HAS BEEN COMPLETED, THE SECOND RESIST IS REMOVED. THE STRUCTURE IS THEN PLATED WITH AN ETCH RESISTANT METAL IN AREAS NOT MASKED BY THE FIRST RESIST. THE FIRST RESIST IS REMOVED AND THE UNWANTED REGIONS OF THE CONDUCTIVE LAYER ARE ETCHED AWAY. THIS METHOD IS PARTICULARLY USEFUL FOR PLATING CONDUCTIVE STUDS IN A MULTI-LAYER PRINTED CIRCUIT STRUCTURE. THE SIDES OF THE STUDS ARE PROTECTED BY THE PLATED RESIST TO PREVENT THE STUDS FROM BEING ETCHED IN THE ETCH STEP.

Inventors

• 👤 K Greene

Bibliographic Details